Electric switch



Oct. 25, 1938. Q T, EVANS ET AL 2,134,179

ELECTRIC SWITCH Filed June 13, 1.935

11 1 2 16 I, 14 Q; 12' as 19 L. 13 r 1 15 15 0 @Xmw MW W 10 m M/ZXQWW1:732 QYXXXM Patented Oct. 25, 1938 UNITED STATES ELECTRIC swrronClarence T. Evans, Wauwatosa, and Herbert E.

Heller, West Allis, Wls., asslgnors to Cutler.- Hammer, Inc., Milwaukee,Wis., a corporation of Delaware Application June is, 1935, SerialNo.26,322 3 Claims. (61. 200-166) This invention relates to electricswitches,

and while not limited thereto is particularly applicable toelectromagnetically operated switches for use in welding controlsystems. Control systems of various types, and particularly weldingcontrollers, require electromagnetic control switches of relativelylarge current carrying capacity which are exceedingly quick acting andare responsive to an energizing current of relatively low value.Electromagnetic switches having a relatively small air gap tend tooperate quickly in response to an energizing current of relatively lowvalue but it is difficult to prevent switches of this character fromreestablishing circuit when deenergized clue to rebound of the movableparts out of open position.

The present invention has among its objects to provide an improvedbuffer device for switches of the aforesaid character which acts tofrictionally dissipate the kinetic energy present in the switch partswhen moved into open position to prevent rebound thereof out of suchposition.

Another object is to provide an improved buffer device of the aforesaidcharacter which is simple and rugged in construction and positive andreliable in operation.

Various other objects and advantages of the invention will hereinafterappear.

The accompanying drawing illustrates an embodiment of the inventionwhich will now be described, it being understood that the embodimentillustrated is susceptible of modification without departing from thespirit and scope of the appended claims.

In the drawing, Figure 1 is a front elevational view of an electromagnetically operated switch having a buffer embodying the inventionassociated therewith;

Fig. 2 is a side elevational view of the operating magnet and buffershown in Fig. 1, and

Fig. 3 is an enlarged sectional view of said buffer.

Referring to Fig. 1, the switch shown therein is of a conventional typehaving cooperating stationary and movable contacts I and 2, the latterbeing mounted upon an insulated section of a rotatable shaft 3 carriedby suitable bearings fixed to an insulating panel 4. Shaft 3 has anoperating magnet 5 associated therewith, said magnet being provided witha magnet frame 6 secured to panel 4, a winding I mounted upon saidframe, and a cooperating armature member 8 which is mounted upon shaft3, or if desired upon a separate shaft, alined with shaft 3.

Armature gpember 8 is operatively connected to shaft 3 by an arm 9 andupon energization of winding 1 said armature member is attractedinwardly from the position shown in Fig. 2 to effect engagement of themovable switch contacts 2 with the stationary contacts I. Upondeenergization of winding 1, armature member 8 and the movable contactscarried by shaft 3 drop out and are arrested without rebound in openposition by the buffer l0.

Buffer Ill includes a cylinder II which is of large diameter relative toits lentgh and a piston l2 movable within said cylinder and fixed to apiston pin I3. The front end of cylinder I l is closed by a wall [4having a forwardly extending projection l5 thereon which is drilled toreceive the piston pin l3, and a cover I6 is secured to the rear face ofsaid cylinder by screws IT to provide a tight enclosure for the pistonl2. Piston l2 has a flat front face and is biased to move forwardly intoengagement with a flat face on the rear of wall M by a spring I 8 heldunder compression between said piston and the cover [6. Said piston mayhave one or more drilled openings I9 therein the purpose of which willbe hereinafter set forth, and the front end of piston pin I3 has a capnut 20 threaded thereon to be engaged by a downwardly extending tailpiece 2| on armature member 8.

The buffer is designed for mounting upon the rear of panel 4, and forthis purpose the front wall I4 of cylinder H has a plurality offorwardly projecting lugs 22 thereon for engaging the rear face of saidpanel. Pane1'4 is drilled to provide an opening for receiving projectionIS on cylinder l l and said panel is also drilled to receive a pluralityof securing screws 23 which are threaded into tapped openings in thelugs 22. It is, of course, apparent that the buffer may be modified toadapt the same for mounting upon the front face of panel 4 or upon themagnet frame 6.

The function and operation of the aforedescribed buffer will now be morefully set forth.

Normally piston I2 is held in engagement with the front wall H ofcylinder H by spring l8 and outward movement of the armature member 8and the switch parts associated therewith is limited by engagement oftail piece 2| with the front face of the cap nut 20 on piston pin l3. Inpractice spring I8 is so designed that the force exerted thereby is onlyslightly greater than is necessary to prevent movement of piston I! outof normal position by the weight of the movable switch parts.

Upon energization of winding 5 armature member 8 is moved into itsattracted position to effect engagement of the movable contacts 2 withstationary contacts and the tail piece 2| on said armature member movesout of engagement with the cap nut 20 on piston pin l3. Upondeenergization of winding 1 armature member 8 and the movable switchparts associated therewith drop out to disengage the movable contacts 2from stationary contacts and immediately upon sufficient separation ofsaid contacts to effect interruption of the circuit or circuitscontrolled thereby tail piece 2| moves into engagement with the frontface of cap nut 20. The inertia of armature member 8 of the movableswitch parts associated therewith then cause inward movement of piston|2 within cylinder against the action of spring l8.

During inward movement of piston |2 within cylinder I the air in saidcylinder is forced from the rear of piston |2 to the front thereofthrough the clearance between said piston and cylinder H and through theopenings IS in said piston. The piston I2 thus acts to retard outwardmovement of armature member 8 and the movable switch parts associatedtherewith to thereby frictionally dissipate part of .the kinetic energypresent in these parts upon engagement of tail piece 2| with cap nut 20,the remainder of the kinetic energy in these parts being stored inspring l8. In practice piston I2 is of such diameter that a slightclearance is provided between the same and cylinder II and the retardingeffect of the buffer device is adjusted by providing one or moreopenings I9 in piston l2 so that said piston moves through a substantialpart of its stroke under the action of the moving switch parts. .Uponcessation of outward movement of the movable switch parts the energystored in spring l8 acts to return piston |2 into engagement with thewall ll of cylinder H. During outward movement of piston H the energystored in spring l8, due to opening of the switch, is frictionallydissipated by the passage of air from the front of said piston to therear thereof and the movable switch parts are thus brought to rest innormal position without rebound. The switch can thus be provided with arelatively small air gap to render the same quick acting and responsiveto an energizing current of relatively low value. v

It should be noted in connection with the foregoing that the bufferdevice never interferes with closing movement of the "switch and theswitch is thus always responsive immediately upon energization of itsoperating winding. It should also be noted that the buffer is soarranged that there is substantialy no sliding movement of the tailpiece 2| with respect to the cap nut 20 upon opening of the switch andthe wear on these parts will thus be negligible.

What we claim as new and desire to secure by Letters Patent is:

1. The combination with a movable switch element biased to interruptcircuit, of a stop member normaly positioned to abut said switch memberupon biased movement thereof into a given limit, said stop member beingmovable out of normal position to permit overtravel of said switchelement beyond said limit and being biased towards normal position toeffect return of said switch element to said limit, and a dash potassociated with said stop member for retarding movement thereof out ofand into normal position, said dash pot including a stationary cylinderhaving an enclosing wall on one end thereof and a piston within saidcylinder fixed to said stop member and normaly located adjacent saidenclosing wall.

2. The combination with a movable switch element biased to interruptcircuit, of a stop member normally positioned to abut said switch memberupon biased movement thereof into a given limit, said stop member being.movable out of normal position to permit overtravel of said switchelement beyond said limit and being biased towards normal position toeffect return of said switch element to said limit and a dash potassociated with said stop member for retarding movement thereof out ofand into normal position, said dash pot including a closed stationarycylinder of large diameter relative to its length and a piston withinsaid cylinder fixed to said stop member and normaly located adjacent oneof the end walls of'said cylinder.

3. In an air break switch, cooperating stationary and movable contactsnormally having only a relatively small air gap therebetween, anoperating element for the latter of said contacts movable in onedirection into a position to effect engagement of said contacts andbiased for movement in a reverse direction to disengage said contactsand means for arresting said operating element without rebound uponbiased movement thereof, said means including a yieldable stop engagedby said operating element upon normal disengagement of said contacts butpermitting said operating element to continue its biased movement withconsequent abnormal widening of the air gap between said contacts andthereafter returning said operating element for restoration of saidnormal air gap between said contacts, and said stop including meansfunctioning during overtravel of said element and during return to suchposition to frictionally dissipate the kinetic energy stored in saidoperating element and to thereby prevent overtravel of said operatingelement upon its return movement.

CLARENCE T. EVANS. HERBERT E. HELLER.

